OH radical formation from the gas-phase reactions of O3 with methacrolein and methyl vinyl ketone

The OH radical formation yields from the gas-phase reactions of O3 with methacrolein and methyl vinyl ketone have been determined from the amounts of cyclohexanone plus cyclohexanol formed when the reactions were carried out in the presence of sufficient cyclohexane to scavenge > 95% of the OH radicals formed. The OH radical formation yields obtained were 0.20−0.13+0.10 from methacrolein and 0.16 ± 0.08 from methyl vinyl ketone. Because of the possibility of indirect formation of OH radicals from the reaction of the HO2 radical with O3, these cited OH radical formation yields must strictly be regarded as upper limits to the direct formation yields of OH radicals from the reactions of O3 with methacrolein and methyl vinyl ketone.